Fuel injector



June 8, 1954 M. J. BERLYN FUEL INJECTOR 5 Sheets-Sheet 1 Filed June 16, 1953 v s h MARTIN J. BERLYN.

ATTORNEY M. J. BERLYN FUEL INJECTOR June 8, 1954 5 Sheets-Sheet 2 Filed June 16, 1953 MARTIN J. BERLYN.

INVENTOR BY wan/L4 5 1 ATTORNEY M- J ERLYN FU NJECTOR Jun 8, 1954 5 Sheets-Sheet 4 Filed J 1953 M G 9 I MARTIN J-BERLYN' MM Y ATTORNEY June 8, 1954 Filed June 16, 1953 M. J. BERLYN FUEL INJECTOR 5 Sheets-Sheet 5 MARTIN J. BERLYN.

INVENTOR ATTORNEY Patented June 8, 1954 FUEL INJECTOR Martin J. Berlyn, Sufl'ield, Conn, assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application June 16, 1953, Serial No. 362,114

jection apparatus therefor.

In the early days of compression ignition engines which operated on the true diesel cycle, the advantages of the conservative maximum firing pressure characteristic of the constant pressure mode of combustion were seriously offset by the hazard of explosions in the blast air compressing and storing means. Furthermore, the air compressor was relatively unreliable. In these early true diesel engines, it was necessary to have available a stored supply of air compressed to a pressure in the order of 1090 p. s. i. and this supply of blast air had to be maintained at such high pressure during operation of the engine by means of an air compressor. The blast air usually constituted as much as to 8% of the total air consumption of the engine; and consequently a considerable percentage of the gross power output of the engine was necessarily diverted for driving the blast air compressor. An

undesirably high specific fuel consumption of the engine accordingly resulted.

In these diesel engines, although a lower blast pressure was required at light engine loads than at full load, the stored supply of blast air had to be continuously maintained at the highest pressure which might from time to time be required.

The practice of compressing and storing the air at high pressure and then reducing it to a lower pressure for use at light loads was exceedingly inefiicient. The part-load economy of the engine was adversely affected because of the even greater proportionate diversion of engine power for driving the blast air compressor under light load conditions of engine operation.

In all these diesel engines, control of the admission of blast air to the injector was effected by a mechanically actuated air valve which could be controlled as to the amount and duration of lift per cycle, the duration being referred to degrees of crankshaft rotation. Since a given setting of the air valve control would admit greatly differing amounts of air per cycle at different speeds of crankshaft rotation, it was necessary to superimpose manual controls to compensate for this; otherwise, a reduction of crankshaft speed would result in the admission of an excessive amount of blast air with consequent killing of the engine. On the other hand, an increase of crankshaft speed would result in a deficiency of blast air and consequent defective combustion.

For the past 25 or 30 years compression ignition engines, frequently referred to as diesel engines, have been fueled by one or more systems of so-called solid injection. In such systems, liquid fuel has been injected at a high pressure of the order of 10,000 p. s. i. through jets or nozzles by hydraulic pressure alone and without any air blast. These engines have all operated substantially on the constant volume combustion cycle and have consequently been characterized by maximum firing pressures of the order of twice the compression pressure. As a result of this pressure rise of about above compression pressure, all modern diesel engines have suffered from a high ratio of maximum firing pressure to mean effective pressure, and have necessarily been of extremely heavy construction. So-called diesel engines have therefore developed into prime movers which, by comparison with gasoline engines, are costly, bulky, and heavy.

In order to reduce the cost, bulk, and weight of compression ignition engines, it is necessary to reduce the ratio of maximum firing pressure to mean effective pressure. One way of achieving this reduction is to return to the constant pressure combustion cycle of the true diesel engine. No method of achieving constant pressure combustion in a compression ignition engine has ever been discovered except by [blast injection of the fuel. Notwithstanding the desirable attributes of the constant pressure combustion cycle engine, it has failed to compete successfully with the constant volume cycle engine for no reasons other than the operating hazards, the unreliability, the expense, and the inefficiency of the blast injection systems available up to this time.

The present invention has for its principal object the provision of fuel injection apparatus incorporating a new and improved blast injection system. Other objects are to provide such apparatus (a) which permits the compression ignition engine to enjoy the advantages of the constant pressure mode of combustion without paying the intolerable penalities exacted by prior blast injection systems, (2)) which is particularly adapted for use with crude fuels, such as low quality liquid'fuels, and suspensions of finely pulverized solid fuels, such as coal, in liquid vehicles, (c) which achieves rapid injection and fine division of fuel particles without recourse to excessively hi h fluid pressures, (d) which achieves a constant pressure combustion cycle and thereby avoids the high cylinder pressures and combustion shock which create such structural and mechanical problems in the contemporary high output compression ignition engines operating on the constant volume cycle of combustion, (e) which avoids the mechanical complication and numerous manual controls previously required to actuate the fuel and air controls of engines employing blast injection systems (f) wherein the blast pressure is automatically proportioned to the varying compression pressure of the engine cylinder, particularly in the case of supercharged engines (9) wherein the amount, by volume, of blast vapor per cycle is proportional to the amount, by volume, of fuel per cycle, the proportional volumes of aid and fuel being independent of th cyclical frequency of injection, (71) which makes possible the entirely automatic adjustment of the quantity and pressure of blast air to the requirements of the engine over the complete spectrum of operating conditions without recourse to mechanically actuated valves in the injector unit, (2') wherein the blast air of each cycle of operation is derived directly from'the working cylinder of the compression ignition engine on. each compression stroke (7') wherein the usual blast air compressor and storage receiver are eliminated, and (7c) wherein high pressure air piping, external to the engine, is eliminated.

In the drawings, Figs. 1 and 2 are schematic diagrams showing the injection system of the invention with its moving components in two combinations of positions assumed at two stages in the cycle of operations. In Fig. 1 the fuel pump is about to begin its delivery stroke and the piston in the engine cylinder is about to begin its compression stroke. In 2 the fuel pump has just completed delivery and the engine piston is at top dead center of its compression stroke. Fig. 3 is an elevational section taken on line 33 of Fig. 6 of an injector embodying the invention. Figs. 4 and 5 are other elevational sections taken on lines 4-11 and 5--5 respectively of Fig. 6. Fig. 6 is a plan view. Figs. 7 through 19 are cross sectional views of the injector taken along the lines 5-49 shown in Figs.

- 3, 4, and 5.

In Figs. 1 and 2 of the drawings, the apparatus of the invention is illustrated diagrammatically. An analysis of these diagrammatic drawings will be helpful in an understanding of the later drawings (Figs. 3-19) of an embodiment of the invention as applied in practice to a fuel injector. Only one cylinder of a two-stroke cycle engine is shown, but it is to be understood that the invented system is equally applicable to a multicylinder engine or to a four-stroke cycle engine.

Referring now to Fig. 1, engine piston 36 is arranged for reciprocation in cylinder 3! in the manner customary in internal combustion engines of the compression ignition type. An in-- jector nozzle 32 provided with spray orifices 33 extends into the combustion chamber. A fuel pump, generally indicated as 34, which includes a plunger 35 reciprocated by a cam (not shown), delivers fuel to the nozzle along a course in a manner hereinafter described in detail. Tank 36 supplies fuel to the pump through passage 31.

Housing 38 contains a cylin rical chamber 39 which serves as an accumulator for compressed air, as later described. Formed in the housing in coaxial relation to chamber 39 are two guide bores H and 52 within which is arranged a hollow multiple piston 43. Within air accumulator chamber 39 and biased against piston G3 is a preloaded spring 44. A third guide bore 45 extends downward through the center of the housing coaxially with bores M and 42, and within the bore is disposed plunger 46 which cooperates with piston 43, as later described. Preferably plunger it is a separate element, and it is so illustrated, but it may be made integral with piston 43. It is to be observed that stem c1 of plunger 55 is of smaller diameter than that of the main body of the plunger so that an annular clearance 48 is provided in the lower part of bore 45. Two more bores 69 and 5! are formed in the unit coaxial with bore 45 and within them are respectively arranged a tappet 52 and a fuel admission valve 53.

Continuing with the diagrammatic drawing shown in Fig. 1, fuel delivered by pump 34 advances through tubing 55 into passage 55 which extends downward through the housing. Passage 55 turns horizontally as passage 53 to cross between bores 29 and 5! to communicate with passage El. Passages 55 and 51 are illustrated as lying in horizontal alignment, but in actual practice they will approach each other at an acute angle. A branch passage 58 leads upward from passage 56 and at its upper end is formed to receive a check valve 59, preferably of the ball type. Branch 58 communicates with passage 88 beyond valve 59. Passage 63 extends horizontally between bores 55 and 49 to communicate with passage 6|. Passages SB and 6! are illustrated as lying in alignment but in actual practice they will approach each other at an acute angle. Passage 8! terminates at vertical bore 52 within which is disposed a shuttle valve, generally indicated as 53, adapted to reciprocate in the bore in response to fuel and compressed air pressures in the manner later described.

Shuttle valve 53, which has three cylindrical lands ti l, 65, and $6 with intermediate reduced portions 5? and E8, is free to move axially in a fluid-sealing fit in bore 82. This valve has a boss 59 at its upper end for abutment with housing wall it when the valve moves to its upper limit of travel, and wall H has a boss 12 extending upward therefrom which acts as a stop for the valve when it moves to its lower limit of travel. A communicating duct it extends axially of the valve from boss 89 to a point where it registers with passage i l when the valve is at its upper limit of travel. The upper end of duct i3 has a plurality of radial ports and its lower end has a plurality of ports 75. The lands of the valve control the passages leading into bore 62 in the manner later to be described. Beyond bore 82 passage M serves as a continuation of the fuel transfer means and leads downward, as passage H, and then horizontally, as passage '55, to bore 5|. Fuel passing through the foregoing system of passages, that is through 54, 55, 55, 53, 69, 61, M, ii, and 18, under conditions later described, impinges upon the differential surface area 79 of valve 53 to lift the latter thus permitting fuel to pass through duct B6 and orifices 33 to the combustion chamber.

Further continuing with the diagrammatic drawing shown in Fig. 1, within housing 38 there is also arranged a compressed air accumulator system comprising air accumulator chamber 39 and a series of passages extending from accumulator 39 to nozzle orifices 33. Passage 3: extends horizontally from the injector nozzle 32 and then turns vertically upward as passage 82. At the upper end of passage 3'2 is disposed a check valve 83, preferably of the ball type as illustrated. Two horizontal branches 53d and lead from the vertical passage 82 to communicates with bore (i2.v continuing; beyond 11011262 are two more air passages as and; 31-, theafirst of; which? extends. upwardj as passage? 38- and turns-inward as: passage 89 to bore 42, and: the other of which extends upward as passage St, then inward, as passage 9|, and then downward aswpassage 92 into-chamber 39. The endiportion of downward-passageQZ-is located in a sleeve 9.3 which projects downward from the top. wall 94 of hollow pistonfls. The lower end of sleeve 93 isspacecl from thebottom wall 95 of'piston1e3. Ilhetop wall 94 is" provided with a plurality of apertures. 95 which. permit air communication between chamber 9"!- of-the-piston and accumulator chamber 39. A lateral. duct es extends horizontally from the-lower portion of, passage 90.430 thetopend portion of bore e2 above shuttlevalve 63. Passage 99 vents the space we below. thev minor diameter of piston 53.

Before describing the-cycle of operation of, the apparatus during fuel injection, the general ob,- servationis made that themoving parts are normally' thrust in one. direction or the other by differential pressures produced on theone: hand by compressed air from the engine piston and on the other hand by v fuel from the fuel pump. Thefurther general observation is made that the pressure of such fuel delivered by the fuelpump generates axial forces to act upon the movable elements which are in. excess of the maximum opposing forces generated by such air pressure.

Referring again to Fig. 1, the engine-piston 3B is at bottom dead center about tobegin its compression stroke; and fuel pump 34 is about to begin itsdeliverystroke. The-conditions prevailing within the apparatus at, this stage are as follows; Air accumulator piston d3, plunger 46, tappet 52, fuel admission valve 53, shuttle valve 53, check valve 59, and check valve 83-.- are' all in down position. An, accumulationofairunder pressure remaining at the completion of. the preceding cycle istrappedin the system. comprising air accumulator chamber 39, piston chamber 81', passages 92, Si, 98,, 8i, and 98 and, the upper portion of bore, 52;. An accumulation of: fuelunder pressure, remaining at the completion-of the preceding, cycle, istrapped between. check valve 59 and fuel admission valve 53. in the, system between them comprising passage til, bore 45, passage Bil, bore 62' (between lands as and 5,5) and passages is; 'i'i, and is. Air in engine cylinder 3! is at low pressure and the same low pressure pertains in the system comprising orinoes-33, duct 83,. passages 81 and $2, branch 8.5,

the bore, (between lands Bit and 65) passages I 36, 88, 89, and space it! in bore 4!. Fuel, in tubing it, passages 55, 5t, and 51 is also at low pressure since the fuel plunger has not yet out on the spill port on its upward stroke.

As plunger 35 cuts off its spill port and begins to deliver fuel, pressure builds up in the fuel tubing 54, passages 55, 56, and 51, and as soon as it exceeds the air pressure exerted downwardly on shuttle valve 53, it begins to displace the latter valve upwardly. As valve t3 moves upwardly, its reduced-portion 5T establishes communication between passages 86 and Bl" thereby toequalize theair pressures in cham er 33 and space lil'i' in bore ll. This is of importance sincethe transfer ofthe air pressure prevailing 7i in accumulator chamber 39 to space lei ofborc 41. causes asubstantial increase in theupward force exerted on the accumulator plunger and a. consequent. diminution of the net downward force, Such diminution of force brings. within practical;limits;the-requirementsofrfuelzpressure necessary to lift plunger 4-62: fromtheibottom limit of its; travel for the; purpose of: fuel charging, as later appears; Just. before. reduced" portion 61 opens communication betweenv passages 86 and 8.: a.1and: 'cutsofi branch185 so that airrat ace cumulator pressure is prevented from escaping throughbranch passages 82, 81, and duct, 8i! into cylinder 31. As the valve 5-31movesupward, duct; 8;: is broughtinto thebalanced. air accumula-tor" system so.- that accumulator chamber pressure is: exerted upon air-check valve 83 tohold it closed. Fuel check valve 59 remains closed at. this stagexbecause of the excess. of trapped fuelpressuregover pump-pressure. Fuel admission valve53' also remains closed atthis stage since the net force exerted upon it is downward;

Refer now to Fig. 2, when shuttle valve; 63 reaches the upper limit of its travel; fuel pressure in tubing 54, passages; 55, 56; 51, and. 5.8 is. built, up by pump 36 to a pressure-in. excess of; that of the fuel trapped under plunger so; that, check valve 59 opens: Fuel. then enters passage 60., bore tiand clearance 48 to displace plungerv 46 upwardly against the combined: bias ofv spring 44 and thediiferential downward force or" air pressure on piston 53. Pistons?! is displaced, upwardly and as it moves intov chamber 39 ittransfers air from the upper side of the piston through apertures 95, chamber 9?, passages 92-, 9|, 9.0, 81; bore 62;, and passages 86', 3t, and as into the space; Hit in bore 42;; and since the volume of the: trapped, air is reduced by the rising piston, its pressure is increased. 'I-appet 52" moves to. the upper limit of its travel because, the fuel pressure, in, passages 55- and ill: isgreater than the fuel pressure in passages an and; 61: by the, amount required to, open, check valve 5.9; Check. valve 83 is still; seated: since the; pressure of air in cylinder 3! transmitted through duct 89- and: passages 81 and 32 has not asyet achieved a value as high: as that of the trapped airin: the balanced accumulator system.

It; should be here-observed that when valve 63 is in; its top position of. travel, ports '55, duct 13, and ports. it.- of shuttle valve 53 establish, communication between the air accumulator system and the differential surface-area T9 of valve 53 through passages- 74', l'l, and i8. Accordingly, the. residual'fuel pressure on such area drops to the pressure in thezairaccumulator system. The prime function of duct'i-t and its associated ports lS tOj provide some lubrication by fuel of thetop land 6.4; of. the-shuttle-valve 63; but it. also serves to make the fuel pressure; on the differential surface" area 1.9 of the valve 53 determinate and nelativelylow:atthis point in-the cycle; of events.

As: the engine piston continues upward from the-position shown in: Fig. 1, the pressure of the airin: the'cylinder 3+ and in passages 3| and 82 continues. to increases. Whensuch pressure ex.- ceeds-the pressureof the, air in the balanced air accumulator system, check valve 85 is forced open and air from cylinderdl passes around reducedf portion 61 of shuttle valve 53- andfollows ina divided-..course, one portion advancing along passages 86-, 88, and 85 into space Elli in. bore and? the; other: portion advancing along passages 8?, st, 95, and 52.2 through: chamber; 91 apertures as: into: chamber 35." As the: air pressure: continues to, increase in cylinder; 31*, the same increasing pressurepertains throughoutthe air accumulator system; In, the meantune fuel pump plunger it continues; its pumpings stroke and; the: fuel pressure increases; to; its maximum 7 pressure to force plunger 45 and piston 43 upward. The fuel storage system comprising tubing 54, passages 55, 56, 51, 58, 68, and 6K, and bore 45 is filled with fuel at maximum pressure.

The fuel pump plunger now uncovers the spill port and there is an immediate drop in fuel pressure in tubing 5 3, passages 55, 55, El, and 58 and the lower portion of bore 5 2. Check valve 59 closes but the position of land 56 of shuttle valve 63 is such that the fuel thus out off remains trapped for an instant in bore 55 and passages 5G and 6!. Because of the fuel pressure drop in passage 51 and the lower portion of bore 52, shuttle valve 63 moves rapidly downward toward its lower limit of travel in response to the air pressure exerted upon its upper end. As valve s2. reaches its lower limit of travel, reduced portion 86 opens communication between passages E! and M and reduced portion e? opens communication between passages 88 and 85.

When passages 88 and 85 are connected, air accumulated at maximum pressure in space ilii is forced through passages 38 and 36 around reduced portion 61 into branch 35, passages 82 and SI, and into the annular recess H32 whence it flows radially inwardly into duct 8=3 through the annular clearance I03 between lip i8 1 and housing portion 35. Simultaneously passages 6i and 14 have been brought into communication so that fuel in the storage system of passages 58, bore 35, and passage 65 (valve 59 now being closed) is forced through passages l4, ll, and it, as will soon be described. The pressure of such fuel acts upon differential surface '59 to lift valve 53. The drop in fuel pressure in bore &5 allows piston 33 to descend in response to the combined forces produced by the air pressure in accumulator chamber 39 and the spring 44. Plunger 48 is displaced downwardly by piston 13 and forces the accumulated fuel around valve 53. here be recalled that fuel pressure in passages 55 and El dropped when the fuel pump spilled and consequently the fuel pressure on the differential area is is opposed to such lesser extent. When valve 53 is lifted, fuel emerges from outlet Iiifi I in the form of a cylindrical sheath coaxial with duct Sii. Compressed air blasted through duct 86, as previously described, intercepts the fuel sheath and it is apparent that a desirable mixture takes place between the pulverized fuel and .h.

fuel which may have been carried to the bottom of the chamber Bl in the accumulator piston 43 by way of duct 93 will be carried out through passage 92 in sleeve 93 and transferred by the moving air through passages 92, 9 l, and 90 around reduced portion El and through passages 86, 88, and 89 into space iiil in bore M under the differential area of the piston.

The spring in fuel check valve 59 is provided to ensure that the ball 46 seats without delay upon the cessation of fuel flow from the injection pump to the fuel accumulator. Check valve 59 is of the type which can be opened only when there is an actual flow of fuel past it in one di- It should rection. If there is no flow of fuel, the valve remains closed.

The large spring 44 is provided in the air accumulator chamber 39 for the following reason: The design of the differential air piston 43 is such that the air pressure acting on its differential area during injection bears a fixed relationship to the air pressure on its upper side. It is desirable that the pressure on the difierential area should be proportionably somewhat higher when the absolute pressure on the upper side of the piston is low. By the provision of the spring, a downward force on the piston is furnished independent of air pressure and the desired end is achieved.

A further reason for providing that the air feeding the differential area under the accumulator piston 4-3 should come from the upper side of this piston is that when the operation of the engine is changed so that the compression pressure in the engine cylinder falls, means must be provided for dropping the air pressure on the upper side of the differential air piston to the new required value. Were it not for the action of the shuttle valve 83, the air check valve 83 would prevent reduction of air pressure on the upper side of the accumulator piston to a value consistent with reduced compression pressure in the engine cylinder.

Referring now to Figs. 3 through 19, the invention is shown embodied in a fuel injector. The same reference numerals, with the addition of a, are applied to the parts in the injector corresponding to the parts shown in the diagrammatic drawings. It is believed, in light of the preceding detailed explanation of the diagrammatic drawings, that no detailed explanation of Figs. 3 through 19 need be given.

While there has been hereinbefore described an approved embodiment of this invention, it

will be understood that many and various changes and modifications in form, arrangement of parts and details of construction thereof may be made without departing from the spirit of the inven tion, and that all such changes and modifications as fall Within the scope of the appended claims are contemplated as a part of this invention.

What I claim is: i

l. A fuel injector of the type described comprising a housing; an orificed nozzle; a fuel accumulator; an inlet passage to supply fuel pumped from an outside source to the accumulator; a first check valve in said passage; a delivery passage from the fuel accumulator to the nozzle; an injection valve controlling said delivery passage; an air accumulator; a piston having a head with opposed pressure responsive surfaces disposed in the air accumulator and a piston stem having a pressure responsive surface disposed in the fuel accumulator; an air passage leading from the nozzle to the air accumulator and having two branches opening into the accumulator on opposite sides of the piston head; a check valve in one of the branches; and a shuttle valve in communication with the fuel inlet and air passages and movable to its opposite limits of travel by fuel pressure and air pressure respectively, said valve controlling the fuel delivery passage and both branches of the air passage.

2. A fuel injector of the type described comprising a housing; an oriflccd nozzle; an injection valve openable inwardly in response to fuel pressure; a fuel accumulator; an inlet pas- =sage to:supply:fue1 :pumped from an outside source -to :theraccumulator; a first :check valve in 'the inlet-passage; a fuel-delivery passage connecting -the fuel "accumulator and the injection valve; :an air accumulator; a differential piston having a hea'd with opposed pressure responsive surfaces of different areas disposed in the -"air accumulator and'a stem extending into the fuel -accunn-ilator, said piston being adapted to move through the air accumulator in response to fuel pressure onthe stemthereby to displace air from one-portion of'the accumulator and to provide a phaitlbcr of increasing size for the reception of air displaced from said one portion of the accumulator; -a passage fromthe nozzle having two branchesopening into the air accumulator on I opposite sides of the piston head; a second *check valve inthe last mentioned passage; a shuttle valve having opposed surfaces thereon to reciprocate the valve in response to fuel and. air "pressure respectively; means connecting the 'fu'el'in-let-passage and oneof the shuttle valveopposed-surfaces ;=means connectingtheair accumu- :lator and the opposite shuttle valve surface; means onthe shuttle valveto control the fiowiof 'fuel from'the fuel accumulator to the injection valve ;-mcanson theshuttlevalve to controlthe flow of air'fromtheair accumulator to the; nozzle; and-means on the shuttle valve to permit the flow of air from the-nozzle to "the air accumulator.

"-3. A fuel injector of'the'type described comprisinga'housing; .anorificed nozzle; an injection valve 'openable' inwardly in response to fuel pressurein-the delivery passage; a fuel accumulator; aninlet passage'to supplyfuelpumped from an outside source to th accumulator; a first checl: valve'in theinlet passage; a fuel delivery passage from the fuel accumulator to the injection valve; an air accumulator; a piston having a head with opposed 1 pressure. responsive surfaces disposed in theair accumulator; a plunger, associated therewith and having. a pressure responsive surface disposed in the fuel accumulator; .a preloaded spring engaging one of the pressure responsive surfacesiof the piston'head; an air passage "from the nozzle havingitwo. branches opening into the air'accumulator on opposite sides of the piston head; a second check .valve in'the air passage; alimitedbore in the 1 housing; a shuttle valve sli'dable in said bore and comprising'a cylindrical memberhaving opposite end pressure responsive surfaces adapted to reciprocate the valve in response to fuel and air pressures respectively; means connecting the fuel inlet passage and one of said end surfaces; means connecting the air passage and the other of said end surface; means on the valvetto; control, the; flow of fuel from the fuel accumulator to the injection valve; and means on "the -v-alveto-control=theflow of air betweenithe air accumulator and the nozzle; said: shuttlevalve moving to :one. limit :of =.tr,avel in response to fuel pressure during delivery of fuel through the inlet passage and cutting off communication between the injection valve and the nozzle and the fuel and air accumulators respectively thus trapping fuel and air in their respective accumulators, said shuttle valve then moving to the other limit of travel in response to air pressure in the air accumulator when fuel pressure on the shuttle valve drops at the com pletion of fuel delivery to the fuel accumulator thus opening communication between the injection valve and the fuel accumulator and between the nozzle and air accumulator, said. piston mov- 'ing in one-direction through the air accumulator in response to fuel prcssure onthe stem thus to displacevair from theportion of the air accumulator which'is decreasing in volume-tothelportion of the air accumulator which is increasing in volume; and-moving in the. other direction through the ai-rac'cu-mulator ingresponse to the pressure ofthe compressed airto force air from the portion of the air accumulator of new decreasing volume and fuel from the fuel accumulator through their respective delivery passages to the nozzle and inj ectionvalve respectively.

4. A fuel injector of the type described comprising ahousing; .an orificednozzle adapted to disperse emulsionof vair and fluid fuel; an air accumulatonan air supply passage from the nozzle to 'theyair accumulator; a check valve in the :air supply passage; a piston reciprocable in the air acoumulatonsaid piston having two axially-opposed pressurexresponsive surfaces of unequalarea; afuelaccumulator, a fuel inlet passage to conductfucl under pressurefrom an outside source .to the fuel accumuiators; a check valve in the fuel inlet passage; a plunger reciprocable inthe fuel accumulator, said plunger being adapted to move in unison with the air accumulator piston; a differential fuel valve; means wherebyusaid fuel accumulator piston, when at its discharge limit of travel, retainssaid differential fuel valve in closed position; a passage from the fuel accumulator to the differential area of the differential fuel valve; a first branch of the fuel inlet passage to communicate "fuel supply'pressure to the majorarea ofthe differential fuel valve; a landed shuttle valve in communication with thevfuelinletpassage and-with the air supply passage,. said shuttle valve having twonaxially opposedsurfaces to provide reciprocation. of the shuttle valve in response toalternating excesses offuelpressure and air pressure on said axially opposed surfaces respectively; means ctr-the shuttle valve tolcontrol the flow of fuel through the passage from thefuel accumulatorrtogthe differential area of the differential fuelvalve; means on the shuttle valve to control the flowof air-throughthe air supplyopassage to thermajoraareaof thezair accumulator piston; means on the shuttle 'valve'to control .theilow of airffromzthe minor area of the air accumulator DlS'GOIlxtO the air supply passage between thev nozzlexand the air accumulator; andmeans on the-shuttle valve to balance the pressure of air between thesmajor and minorareasof the air accumulatorpiston.

1.5. A fuelinjectorofthe type described comprising a housing; an orificed nozzle adapted to dispersean emulsion of air. and fluid fuel; an air accmn-ulator; an air supply-passage from the nozzleto'the air accumulator; a check valve in the air supply passage; a-pistonin the air accu-mulator; said piston having two axially-opposed pressure rcsponsive surfacesof unequal area; a fuel accumulator; 1a fuel inlet passage to conduct "fuel under pressure from an outside source to the fuel accumulator; a check valve in the fuel inlet passage; a plunger in the fuel accumulator, said plunger being adapted to move in unison with the air accumulator piston; a difierential fuel valve; a tappet to retain the differential fuel valve in closed position when the fuel accumulator piston is at its discharged limit of travel; a passage from the fuel accumulator to the differential area of the differential fuel valve; a landed shuttle valve having two axially opposed surfaces to provide reciprocation of the 11 shuttle valve in response to alternating excesses of fuel pressure and air pressure on said axially opposed surfaces respectively; a first branch of the fuel inlet passage to communicate fuel supply pressure to the major area of the differential fuel valve; a second branch of the fuel inlet passage to communicate fuel supply pressure to the first of the axially opposed surfaces of the shuttle valve; means on the shuttle valve to control the flow of fuel through the passage from the fuel accumulator to the differential area of the differential fuel valve; means on the shuttle valve to control the flow of air from the air supply passage to the major area of the air accumulator piston; means on the shuttle valve to control the flow of air from the minor area of the air accumulator piston to the air supply passage between the nozzle and the air accumulator; means on the shuttle valve to control the flow of air between the major and minor areas of the air 1 accumulator piston; a passage communicating air pressure from the major area of the air accumulator piston to the second of the axially opposed surfaces of the shuttle valve; and means whereby any accretion of fuel in the air accumulator is expelled through said nozzle.

6. A fuel injector, according to claim 5, having a passage from the plunger bore to deliver any excessive charge of fuel out of the injector.

'7. A fuel injector of the type described comprising a housing; an orificed nozzle adapted to disperse an emulsion of air and fiuid fuel; an air accumulator; an air supply passage from the nozzle to the air accumulator; a check valve in the air supply passage; a piston reciprocable in the air accumulator, said piston having two axially opposed pressure responsive surfaces of unequal area; a fuel accumulator, a fuel inlet passage to conduct fuel under pressure from an outside source to the fuel accumulator; a check valve in the fuel inlet passage; a plunger reciprocable in the fuel accumulator, said plunger being adapted to move in unison with the air accumulator piston; a differential fuel valve; means whereby said fuel accumulator piston, when at its discharge limit of travel, retains said differential fuel valve in closed position; a passage from the fuel accumulator to the differential area of the differential fuel valve; a first branch of the fuel inlet passage to communicate fuel supply pressure to the major area of the differential fuel valve; a landed shuttle valve in communication with the fuel inlet passage and with the air supply passage, said shuttle valve having two axially opposed surfaces to provide reciprocation on the shuttle valve to control the flow of air from the minor area of the air accumulator piston to the air supply passage between the nozzle and the air accumulator; and means on the shuttle valve to balance the pressure of air upon the major and minor areas of the air accumulator piston.

8. A fuel injector of the type described comprising a housing; an orificed nozzle adapted to disperse an emulsion of air and fluid fuel; an air accumulator; a check valve in the air supply passage; a piston reciprocable in the air accumulator, said piston having two axially opposed pressure responsive surfaces of unequal area; an air supply passage from the nozzle to the air accumulator including two branches, one of which leads to the larger of the opposed pressure responsive surfaces and the other of which leads to the smaller of the opposed pressure responsive surfaces; a fuel accumulator; a fuel inlet passage to conduct fuel under pressure from an outside source to the fuel accumulator; a check valve in the fuel inlet passage; a plunger reciprocable in the fuel accumulator, said plunger being adapted to move in unison with the air accumulator piston; a differential fuel valve; means whereby said fuel accumulator piston, when at its discharge limit of travel, retains said differential fuel valve in closed position; a passage from the fuel accumulator to the differential area of the differential fuel valve; a first branch of the fuel inlet passage to communicate fuel supply pressure to the major area of the differential fuel valve; a landed shuttle valve having two axially opposed surfaces to provide reciprocation of the shuttle valve in response to alternating excesses of fuel pressure and air pressure on said axially opposed surfaces respectively; a second branch of the fuel inlet passage to communicate fuel supply pressure to the first of the axially opposed surfaces of the shuttle valve; a passage communicating air pressure from the major area of the air accumulator piston to the second of the axially opposed surfaces of the shuttle valve; means on the shuttle valve to control flow of fuel through the passage from the fuel accumulator to the differential area of the differential fuel valve; means on the shuttle valve to control the fiow of air through the air supply passage to the major area of the air accumulator piston; means on the shuttle valve to control the flow of air from the minor area of the air accumulator piston to the air supply passage between the nozzle and the air accumulator; and means on the shuttle valve to balance the pressure of air between the major and minor areas of the air accumulator piston.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,625,436 Berlyn Jan. 13, 1953 

